Preserve quoted cron expressions in frontmatter updates

[Copilot]

UpdateWorkflowFrontmatter could emit unquoted cron expressions after YAML marshaling, producing invalid workflow frontmatter during mutations such as gh aw mcp add.

• Frontmatter serialization

  • Apply the existing QuoteCronExpressions post-processing before reconstructing the workflow file.
  • Preserve cron values such as:

    cron: "0 14 * * 1-5"

• Regression coverage

  • Verify scheduled workflows retain quoted cron expressions while applying unrelated frontmatter updates.

• Fixes [go-fan] Go Module Review: goccy/go-yaml #55333

---

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Run: https://github.com/github/gh-aw/actions/runs/32777439671

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[github-actions]

✅ PR Code Quality Reviewer completed the code quality review.

No actionable PR review findings; the patch looks correct and I did not submit review comments.

🔎 Code quality review by PR Code Quality Reviewer

[github-actions]

🧠 Matt Pocock Skills Reviewer has completed the skills-based review. ✅

🧠 Reviewed using Matt Pocock's skills by Matt Pocock Skills Reviewer

[github-actions]

✅ Test Quality Sentinel completed test quality analysis.

Test Quality Sentinel skipped because pre-fetch PR data was unavailable: unable to fetch test file diff

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[github-actions]

✅ Ponytail Reviewer completed successfully!

Lean already. Ship.

Generated by Ponytail Reviewer for #55502

[github-actions]

✅ Design Decision Gate 🏗️ completed the design decision gate check.

No ADR enforcement needed: PR does not have the implementation label and has only 23 new lines of code in business logic directories (threshold is 100).

🏗️ ADR gate enforced by Design Decision Gate 🏗️

[Copilot]

Pull request overview

Fixes #55333 by preserving valid quoted cron expressions during frontmatter mutations.

Changes:

• Post-process marshaled frontmatter with QuoteCronExpressions.
• Add regression coverage for unrelated updates to scheduled workflows.

Show a summary per file

File	Description
pkg/parser/workflow_update.go	Re-quotes cron expressions after YAML marshaling.
pkg/parser/frontmatter_helpers_test.go	Verifies cron quoting and updates are preserved.

Review details

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• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

[github-actions]

Comment Memory

reviewed_at: 2026-08-24T00:00:00Z
review_event: COMMENT
top_themes:
  - no actionable issues in changed lines
files_reviewed:
  - pkg/parser/frontmatter_helpers_test.go
  - pkg/parser/workflow_update.go
comment_count: 0

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[github-actions]

Skills-Based Review 🧠

Applied /diagnosing-bugs and /tdd — the fix is correct and well-tested. Approving.

📋 Key Themes & Highlights

Positive Highlights

• ✅ Root cause properly addressed: QuoteCronExpressions is applied immediately after yaml.Marshal, which is exactly where cron values get unquoted
• ✅ Regression test is present, descriptive, and follows the existing Arrange/Act/Assert pattern in this file
• ✅ The fix is a single-line surgical change — minimal blast radius
• ✅ Test validates both the cron preservation and that the unrelated frontmatter mutation (engine: copilot) still applies, confirming no side effects

Minor Observation

The test uses assert.Contains to check that the output contains cron: "0 14 * * 1-5". This is correct but does not verify the full reconstructed YAML structure. That said, it is consistent with how the neighbouring tests in this file are written, so it's the right style call here.

🧠 Reviewed using Matt Pocock's skills by Matt Pocock Skills Reviewer · copilot · sonnet46 · 21.8 AIC · ⌖ 9.75 AIC · ⊞ 7.6K
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[github-actions]

The fix is correct and well-placed. QuoteCronExpressions is applied immediately after YAML marshaling (where go-yaml strips quotes from cron strings), and the regex safely skips already-quoted values by requiring the value to start with a digit. The new integration test validates the round-trip preservation. No blocking issues.

🧵 Reviewed using Impeccable skills by Impeccable Skills Reviewer · copilot · sonnet46 · 17.5 AIC · ⌖ 8.98 AIC · ⊞ 6.2K

[github-actions]

Excellent work, @Copilot! 👋 This PR correctly addresses the cron expression quoting issue identified in the Go Fan review (#55333).

Your changes do exactly what is needed:

✅ Implementation — Added the missing QuoteCronExpressions() call after YAML marshaling in UpdateWorkflowFrontmatter, matching the pattern already used elsewhere in the codebase.

✅ Regression Coverage — New test TestUpdateWorkflowFrontmatterQuotesCronExpressions verifies cron values stay quoted after unrelated frontmatter updates.

✅ Focused & Minimal — One-liner fix + focused test, no unrelated changes.

This PR is ready for review and looks great for merge.

Generated by ✅ Contribution Check · copilot · auto · 54.3 AIC · ⌖ 4.04 AIC · ⊞ 9.3K · ◷

[gh-aw-bot]

gh-aw-pr-sous-chef
@copilot PR Sous Chef triage: this PR still needs forward progress before maintainer investigation is likely to be productive.

Please use the pr-finisher skill and do one focused follow-up pass on this PR.

• review the latest maintainer and reviewer feedback, then either push the smallest needed follow-up or reply in-thread if no code change is still required
• refresh the branch if needed and run make fmt if you touch code
• hand back only after the branch is ready for re-review

I also attempted a branch refresh for this PR in this run.

Run: https://github.com/github/gh-aw/actions/runs/32777439671

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